This invention relates generally to rotating water sprinklers used for irrigation purposes. More specifically, this invention relates to an improved rotating sprinkler, particularly of the so-called large gun type, including a reaction drive member for interacting with a projected water stream to rotate the sprinkler in steps and thereby alter the azimuthal direction of the water stream.
Rotating water sprinklers in general are known in the art for use in supplying irrigation water over a substantial surface area. Such sprinklers typically comprise a sprinkler body supported for rotation by a bearing assembly which is in turn adapted for connection to the end of a water supply pipe. Irrigation water is supplied from the supply pipe through the bearing assembly and further through the sprinkler body to a discharge outlet or nozzle from which the water is projected outwardly with a selected angle of upward inclination. A drive arm is pivotally mounted on the sprinkler body and is biased to move a deflector spoon cyclically into interrupting engagement with the projected water stream such that the water stream imparts a torque to the spoon which is transmitted to the sprinkler body to rotate the sprinkler in a series of relatively small rotational steps thereby altering the direction of throw of the projected water stream. This stepwise movement can be allowed to continue through repeated full-circle rotations, or alternatively, if desired, a suitable reversing mechanism of conventional design can be provided to reverse the direction of rotation repeatedly within the limits of a preselected arcuate path.
In a rotating sprinkler of the so-called large gun type used typically in agricultural sprinkler systems, the sprinkler body comprises a relatively large range tube for passage of a relatively high flow of water and for projection of the water a relatively substantial distance from the sprinkler. In this type of sprinkler, the pivoted drive arm typically comprises a reaction arm counterweighted to move a deflector spoon vertically into interrupting engagement with the projected water stream to rotate the range tube in steps with respect to the supporting bearing assembly. If part-circle rotation is desired, a cam mechanism responsive to the rotational position of the range tube moves a reversing cam in front of the projected high flow water stream resulting in a relatively high reaction force for rapidly rotating the range tube back through the preselected arc whereupon the reversing cam is withdrawn from the water stream and normal stepwise rotation by operation of the reaction arm is resumed. Commercial examples of the foregoing type of so-called large gun or reaction drive sprinkler are the Model 102 and Model 103 Rain Guns manufactured by Rain Bird Sprinkler Mfg. Corp. of Glendora, California.
A variety of problems and disadvantages are encountered, however, with reaction drive sprinklers of this general type. For example, the reaction arm and the camming mechanism constitute separate structures for use in rotating the sprinkler respectively in opposite directions within the preselected arc, thereby increasing the overall cost and complexity of the reaction drive sprinkler. Moreover, the high reaction forces arising from engagement of the reversing cam with the high flow water stream cause an extremely rapid reverse rotation of the range tube wherein this rapid motion can result in excessive wear to the bearing assembly and/or damage to the various mechanical components of the sprinkler. Further, the rate of rotation in both directions within the preselected arc tends to be at least partially dependent upon the pressure of water supplied to the sprinkler, and this pressure can vary significantly, particularly when multiple sprinklers are coupled at different terrain elevations to a common water supply line.
Still further disadvantages are encountered with respect to interrupting the high flow water stream with the reaction arm. More specifically, interruption of this high flow water stream knocks down a portion of the stream thereby reducing the capability of the sprinkler to provide adequate irrigation at substantial distances. In addition, however, a significant quantity of dirt, grit, or other particulate is entrained with the water stream and impacts the deflector spoon at a sufficient velocity to result in relatively high abrasion of the spoon. Accordingly, the deflector spoon is normally provided as a separate replaceable component mounted on the reaction arm and formed from an abrasion-resistant material, such as bronze or the like.
A variety of modified reaction drive sprinkler constructions have been proposed for alleviating or reducing some of the aforementioned problems encountered particularly with sprinklers of the large gun type. For example, consolidation of the reaction arm and the camming mechanism into a single reaction arm structure having two oppositely oriented deflector spoons has been proposed wherein the spoons interrupt the projected water stream for respective driving of the range tube in opposite directions. However, this reaction arm structure has required a relatively complicated mechanical mounting arrangement for accommodating the normal pivoting movement thereof in addition to selective lateral shifting of the arm to align the different spoons with the water stream. Alternatively, sprinklers have been proposed wherein a secondary nozzle is provided through which a relatively low flow water stream is discharged, and the reaction arm and camming mechanism interrupt this lower flow water stream to drive the range tube reversibly with lower forces within the limits of the preselected arc. While sprinklers of this latter type advantageously provide driving forces of lower magnitude and experience significantly reduced abrasion problems, they still have relied upon mechanically complex drive structures which undesirably increase the cost and complexity of the sprinkler.
There exists, therefore, a need for an improved reaction drive sprinkler particularly of the large gun type, having a single reaction arm of simplified construction for reversibly rotating the sprinkler with relatively low driving forces and without interrupting the high flow water stream projected from the sprinkler. The present invention fulfills this need.